Transfer case for power transmissions



5 Sheets-Sheet 1 c; J. BocK TRANSFER CASE FOR POWER TRANSMISSIQNS FiledJune 3. 1942 v Snoentor I 6,224/ 306k July 25, 1944.

l Gttom'egs f www 'July 25, 1944.

C. J. BOCK TRANSFER CASE FOR POWER TRANSMISSIONS Filed June 3, 1942 5Sheets-Sheet 2 (Ittomegs July 25, 1944.

c. BooK 2,354,3'00

TRANSFER CASE FOR POWER TRANSMISSIONS s sheets-sheet :s

Filed June s, 1942 lllll :inventor y Cb?! @of Patented July 25, 1944'raANsFEa ossa Foa rowEn 4 TnANsmssloNs Carl J. Bock, Birmingham, Mich.,assignor, .by

mesne assignments. to General Motors Corporation, Detroit, ware 'I'hisinvention relates to multiple drive axle vehicles and more particularlyto road vehicles having steerable front wheels which can be driven toaugment normal `drive through the rear wheels under unusual operatingconditions.

A type of vehicle for which the improved structure is especially adaptedis the military combat car having eight road wheels arranged in two setsand on a pair of tandem rear drive axles and a pair of tandem frontsteerable drive axles with a power plant to drive one of the rear axlesand one of the front axles and a companion power plant to drive theremaining front and rear axles. In such arrangement each power plantincludes an internal combustion engine and a variable speed'transmissionhaving selective forward and reversev drive settings together with atransfer mechanism through which power from the trans- 4 missionisdivided between front and rear exles.

According to the present invention: the transfer mechanism is coupledvsolidly with the rear axle at al1 times and incorporates an overrunningclutch drive to the front axle. Two enel-walr clutches are employed, onefor forward drive and the other for reverse drive, and clutch selectionis effected conjointly with the forward and reverse settings of thevariable speed transmission. In a preferred embodiment, clutch selectionconsists essentially of taking out of action either one of a pair ofopposing springs so that the force of the other spring assists inestablishing coupled` relationv of the desired set of clutchingelements.l

More particularly the selector springs serve to condition theparts forpositive clutch settings i' and remove the uncertainty of instant andcomplete drive coupling. Inertia or other forces which l otherwise mightinterfere are effectively overfy come by the spring pressure.

Multiple axle drive is always available automatically when' needed.Drive through all axles generally is required only when the rear solidlycoupled axle'tends to overrun the front axle, as A when operation insoft ground or under heavy load vcauses the reartraction wheel to slipor spin. The one-way clutch then picks upl the drive and directs it tothe front axle without calling on the car operator forattention.Ordinarily when the vehicle is traveling at reasonably fast speed onsmooth pavement the front axle slightly overruns the rear axle and drivethrough the rear laxle alone is suiiicient and desirable for' ease andsafety in steering. The slight overrun occurs normally 'because thefront steerable' .wheels travel in longer arcs than the trailing wheels.

Mich., a corporation of Dela- Application June 3, 1242, Serial No.445,627

13 claims. l(ci. lso-23) the front wheels there could be no overrun in'the absence .of rear wheel slip, but as a practical matter exacttracking seldom occurs and even on straight stretches of highway the ve-.hicle driver ordinarily is operating the steering gear all the time thevehicle is moving. However, the important fact is that the mechanismoperates automatically .to afford multiple axle drive for hard pullingand to disconnect steering axle drive for safe high speed steering onsharp curves. i l

Fora better explanation of the novel features reference willbe made toa.preferred embodiment illustrated in the accompanying drawings whereinFigure 1 is a plan view showing the general layout of a two enginemultiple drive axle arrangement; Figures 2 and 3 are enlarged 'sectionalviews taken on lines 2-2 and 3-7-3, respectively, of Figure j1; Figure 4is a sectional view of the power divider taken on line 4-4 of Figure 2and Figure 5 isI a section on line 55 of Figure 2.

Forthe purpose of illustration the attached drawings show the usualchassis frame assembly v i supported by any suitablev spring arrangementupon four axles, `each including a. differential and road wheels onopposite ends. In the case of an armored combat car of the tank typethebottom o! the body hull, instead of 'a conventional chassis iframe, canbe spring supported on the axles.

The longitudinal spacing between the axles may be varied to suit designrequirements but in any event in the case of a four axle vehicle, there.would be involved a rearward rear axle 2 and a forward rear axle Itogether with a rearward front axle 4 and a forward front anxley 5, eacho! the front axles having its road wheels swiveled on the usualkingpins. The steerablewheels, 'of course, need. to be interconnected bysteering linkage of suitable type. At the rear of the vehicle two powerplants are mounted in side-,byside relation. The power plant on therighthand sideoi' the vehicle includes the engine 6 and a variable speedtransmission 1.- The 4variable speed transmissionl proposed for use isof anautomatic type known in the automotive trade A as the Hydra-Matictransmission and having selectlvesettings from neutral position toforward speed and reverse drive.- For effecting manual setting of theon, a. -rockshaft extends v through one casingsside wall with a crankarm con- 'nected by linkage, a part of which is shown at l. leading toan operating lever (not shown) at the driver control station. Either thesame or a 0f course', if the rear wheels would exactlytrsck ss similarhand control leverls connected by linkvehicle. The output end of thetransmission I6- is connected by a universally jointed propeller shaftI2 to the power divider mechanism enclosed within a casing I3. The drivefrom the divider I3 is rearwardly through a propeller shaft I4 to theforward rear axle 3 and is sent forwardly through the jointed propellershaft sections I5 and I6 to the forward front axle 5. Power from `thecompanion transmission mechanism 1 is delivered through a universallyjointed propeller shaft I1 to the transfer case I8 where it is dividedand sent through the jointed propeller shaft sections I9 and 20 t0 therearmost rear axle 2 and through the jointed propeller shaft 2I to therearward front axle 4.

Except for their arrangements to fit the right and left-hand sides ofthe vehicle, transfer casings I3I and 'I8 and their included mechanismsare identical in structure. Each includes a train of intermeshinghelical gears numbered 22, 23, 24, 25, l26 and 21 arranged as shown inFigure 2 for transmitting the drive from theengine to the axles inone-to-one ratio and for presenting the output drive shafts in axialalignment with the respective axle differentials to be driven. As bestindicated in Figure 4, all of the gears except that numbered 21 are ofidentical design in order to promote interchangeability and low costproduction. Each gear is mounted on a supporting shaft which in turn isrotatable in suitable bearings secured in alignment in openings inopposite walls ofthe casing, with conventional cover caps for theopenings. The input shaft 28 to be driven the rear axle tend to overrunthe steerable wheels on the front axle.

It has been found that driving thrust of the helical gears alone isunreliable for obtaining instant smooth transfer of drive and a nicelyfull fitted ratchet tooth engagement. Especially under criticaloperating conditions which compel or result in sudden changes in poweror brake application, the behavior `of a free iioating gear becomeserratic and the ratchets are not always inposition to pick up front axledrive. A slight constant pressure is needed to produce a workablestructure and insure proper driving relation. The necessary assistingforce can be had with the use of spring pressure. To provide for theapplication of spring force selectively in either direction the slidergear 21 is formed with an annular groove to which is fitted a shifterfrom the power plant is formed with Vexternal teeth 29 fitted tointernal teeth on the gear 22. Inasmuch as the supporting shafts 30, 3|and 32 for the gears 23, 24 and 25, respectively, transmit no torqueload, the cost of forming external teeth thereon is eliminated by ttingeach shaft with a radial stud or pin 33 to engage the internal teeth ofits supported gear and thus key the gear on the rotatable supportingshaft. The

drive gear 26 has its' internal teeth ntted to external teeth 34 on thedrive shaft 35 which extends rearwardly through the wall of the casingfor solid drive coupling with a rear driving axle. If desired thecoupling between the drive shaft 35 and its driven. propeller shaft mayinclude a parking brake drum 36 for cooperation with a contractiblebrake bandl1.

A A front axle propeller shaft is coupled with the drive shaft 3B havingbearing support in opposite walls of the divider casing and looselymounting thereon the axially shiftable drive gear 21. On opposite facesof the slider gear 21 are formed the ratchet tooth one-way clutchingelements 33 and 40, respectively, which are adapted to be coupledselectively with complementary clutching elements 4I and 42 flxedon thedrive shaft 3l in axially spaced apart relation on opposite sides of theslider gear-21. The clutching elements 40 and 42 provide a one-way drivefor forward speed .when the drive gear 21 is urged towardthe right" inthe drawings, while the clutching elements 33' fori; 43 enclosed Withinthe transfer 4casing and having its head mounted on a shift rod 44slidable in bearings in opposite walls of the casing. A pair of coilsprings 45 and 46 surrounding the rod 44 are arranged in opposition toeach other and bear at their inner ends on thrust washers 41 and 48,respectively. These Washers loosely encircle the shift rod 44 and in theintermediate or neutral position of the parts engage on opposite ends ofthe head of the shifter fork 43. If the balance of .the springs isdisturbed, as by taking either out of action, the remaining activespring will then urge the shifter rod 43 to one side or the other as thecase may be t'o establish forward or reverse selection and condition thedrive for one-way clutching relation between the drive gear 21 and driveshaft 38.

For controlling selection of the' forward clutching elements 4U and 42and reverse clutching elements 39 and 4I, Figure 5 shows a rock lever 49having a forked headv at its free end to extend between and engage thebearing washers 41 and The level` 49 may be retained in either positionby mounting in its oppositeend a spring pressed,`

detent 5I adapted to' ride over and engage on opposite sides of alocating abutment 52 forming a fixed part of the housing cover. The rocklever 49 is fixed or keyed on an operator controlled shaft 53 whichextends through the wall of the transfer casing and carries a crank armfor connectlon preferably with the control linkage of the variable speedtransmission whereby the forward and reverse setting of the transmissionslmultaneously effects a corresponding setting in the power divider. Asseen in Figure 1 the interconnecting linkage for the selector mechanismin the transfer box I 3 includes a link 54 connected to a transverserockshaft 55 in turn Joined by a link 56 with the control linkage 8.Similarly a link 51 connects the control mechanism for the transfer caseI3 with a transverse rockshaft 58 from which a link 59 leads controllinkage 9.

1. In a power divider, a train of gears,l a primary drive shaft solidlycoupled to one of said clutching elements on opposite sides of thegear,- a shifter device engageable with the gear foi" to thetransmission .nimm the ums-selectively mrc coupled renacewitheitberofsaid clutchingelementaa pairof devicesactlvetogetlterto grelation solely under the influence of the contacting active springdevice.

I. In apower transmitting device of acter described, a pair ofoverru'nning drive clutch devices arranged for forward drive setting andreverse drive setting respectively, a selector member operable on saiddevices to select either forward or reverse drive settings. spring.means .arranged reailiently to urge the selectormembe'r 'into forwarddrive setting, other springmeans arranged astaaoo -ontheshaftfor thecharresilientlytoiirgetheselectormemberintoreverse l drive setting andcontrol mechanism divorced from direct motion transmitting connectionwith the selector member and'operable on said spring means to enableselective operation of the selector 3. In a acter described, a pair ofoverrunning drive clutch devices arranged for forward drive setting andreverse drive setting-respectively,.a selector meniber operable on saiddevices to'selectneither forpower transmitting device the charward orreverse drive settings, itv pair of'springs v active on the ,selectormember in opposition to one another to balance the selector member inneutral setting and means operative on said springs to throw them out ofneutral balancing relation and effect resilient biasing of the selectormember to one or the other of the drive setting relations solely underspring influence and without direct connection between the selectormember and said 4. A power divider betweenv a pair of .drive shaftsoperable ineither forward or reverse iisections, including a solid tageoi! for one shaft,

running clutch for the other shaft,'a clutch selector operative toestablish drive setting of either of said clutches, resilient meansactive to bias the selector to forward setting, other resilient means'active to bias the selector to reverse setting and means independent ofsaid selector and common to both resilient means to control the actionthereof.

5. -A power divider between a pair of drive shafts Y a forwardoverrunning clutch and a reverse overoperable in either forward orreverse directions; 5o

including a solid take off for one shaft, a forward and to-at least one`the operative setting of axially shiftabl! mounted loosely adjustmentin 'one direction to couple the forward dve clutch elements and foradjustment in the opposite direction to couple the reverse drive clutchelements. a shifter operatively ments and being connected with the drivegear, apair of resilient members arranged to exert opposing forces onthe shifter, one directing the shifter inone direction and the otherdirecting direction and means operable selectively on said members tolrender either one inactive, s aid means having no operative connectionwith the shifter and being operable solely on said members.

1. In a power drive arrangement, a transmission having forward andreverse drive settings and control mechanism for selecting the drivesetting, a power divider. through which delivery of driving power fromthe transmission is transferred to a pair ofdrive shaftsvand in whichthe "drive to one of said shafts includes an overrunning clutchoperative for forward speed setting and an overrunning clutch operativefor reverse speed setting, control mechanism for selectively settingsaid'clu'tches for drive through one or the other' thereof, andl meansinterconnecting the last mentioned control mechanism with the rstmentioned control mechanism ,for conjoint operation of the mechanisms intheir selection of forward and reverse settings respectively. f 8. Inapower'drive arrangement, a transmission having forward and reverse`drive settings and control mechanism for selecting the drive setting, apower divider for transferring the drive from the transmission to aplurality" of drive shafts, a pair of one-way clutches'independentlyoperable to transmlt'drive to one of the shafts. one for forward driveand the other for reverse drive, a selector operatively associated with.said

clutches, a pali` of opposed springs acting on the selector and servingto urge the selector to for' wardf or-reverse settings respectively,means to render either spring ineil'ective for selector actuation underinfluence of the other spring and an interconnection between said meansand said transmission control mechanism to compel unison e selection'of=forward and reverse settings for the on and divider. 'i 9. In a multipleaxle vehicle, a set of front steering drive axles and a set of reardrive axles.

a pair of power plants each including an engine. a-selective forward andreverse tonl and a power divider for transferring engine power from itstransmission to at least one of the rear axles of the front axles withsaid power dividers with drive connected to different front andrearaxles, each power divider having solid drive connection with itsdriven rear axle and a one-way drive conlnection .with its driven frontaxle and said onewa! drive connection including a pair of over runningclutches, one operative for and the other for reverse drive,

forwardl drive a selector for clutches and mans responsive to theselective forward and reverse setting of thetransm'ission forregulating'saidselector.- A

10. In combinatioma power having forward and reverse dxivesetting's,drive selector mechanism therefoi-,a power divider drivenfromthetransmissionincludingapdrofoutputshafts,adrivengearshiftablymonntedononeof said shafts, a-for'ward driveone-way chitch and areversedrlveoneway sides of the driven-gear forselective coupling the shifter in the Opposite respect toeach other therespective clutch,bothilxedonsaid` thereto, resilient biasing meansactive on said gear to shift the same into coupling relation with theforward drive one-way clutch, other resilient biasing means active onthe gear to shift the same into coupling relation with the reverse driveoneway clutch, means to unload one or the other of said resilientbiasing means, and means operatively connecting said unloading meanswith the forward and reverse drive selector mechanism of said powertransmission.

ll. In combination, a driven shaft having fixed thereon in axiallyspaced relation, a right-hand one-way driver'and a ieft-handonewaydriver, a vfloating driving gear rotatably and shlftably mounted on theshaft between said one-way drivers and provided with one-way drivers onopposite faces thereof to mate with the aforesaid one-way drivers, agear shifter member operable in opposite directions to. carry said gearaxially into either right-hand or left-hand one-way driver couplingrelation, a pair of opposed springs engaging the shifter member inbucking relation and tending to center the gear in non-driving relationto bothdrivers and means operable, without direct connection on theshifter member, to deflect i the opposing force of either springselectively and .enable .the resilient force of the other spring toestablish one-way drive connection between the driving gear and drivenshaft..

12. In combination, a driven shaft having fixed thereon in axiallyspaced relation, a right-hand one-way driver and a left-hand one-waydriver, a floating driving gear rotatablyv and shiftably mounted on thes haft between said one-way aasaaoodrivers and provided with one-waydrivers on op posite faces thereof to mate with the aforesaid one-waydrivers.l a gear shifter member operable in opposite directions to carrysaid gear axially into either right-hand or left-hand one-way drivercoupling relation, resilient biasing means active on said shifterin'opposite directions to center the same in non-driving neutralpositionand means operable, without direct action on the shifter member,to cancel the action of the biasing means in one direction or the otherfor selectively conditioning the parts for drive through either theright-hand or the left-hand one-way driver.

13. In combination, a driven shaft having fixed thereon in axiallyspaced relation, a right-hand one-way driverand a' left-hand one-waydriver. a floating driving gear rotatablyvand. shiftabl! mounted on theshaft between said one-way drivers and provided with one-way driversonopposite faces thereof to mate with the aforesaid' one-way drivers,helical driven teeth on-said gear which set Yup a torque thrust towardthe right or the left depending on rotational drive direction of. saidgear and tend to bias the gear toward one-way driver coupling 'in eithercase, and means to supplement said torque thrust including a pair ofoperating members exerting resilient forces in opposite directions onsaid gear and a control device therefor independent of direct connectionwith the gear and operably related to the rotative drive direction, ofsaid gear to imbalance the member exerting forces on said gear.

CARL J. BOCK.v

